When a word has a red squiggly line under it (meaning the spelling cannot be recognized by the spell checker) and I right click it (or place the cursor inside the word and press the context menu key), it takes 3-7 seconds every time before the context menu is displayed, if the word is "formatted" as Danish. If the word is "formatted" as English (USA), it takes 1-2 seconds (still consistently). 

Here are some specifics: I tested with the word "Lisp-agtigt" (which is a valid Danish word), marked as Danish, and that gives response times at around 5 to 7 seconds; if I test with a gibberish word "slfiouw", again marked as Danish, the context menu comes up after 3 seconds.

It should go without saying that this is annoying as it stops you in the process of writing; you just want to add the valid word to the dictionary but have to wait up to 7 seconds to do that. The display of the context menu ought to be instantaneous, of course, or at least under 500 ms or so.

I would like to give a list of installed extensions, in case one of them could be the culprit, but I don't know how. Anyhow, I only have extensions that came bundled with LibreOffice. And there is no obvious way to disable them via the user interface, so I can't try disabling them to see if that solves the problem.

I am not able to compile LibreOffice myself to do any debugging, as there are no functional instructions on how to do that successfully and consistently on Windows. I have spent days earlier trying to compile but had to give up in the end.

I am not using 5.3.0.3 as it has a major bug (Bug 105844) that prevents me from using it.